Lock-mortising chisel



(No Model.)`

1. L. 4FOX.

LOCK MORTISING GHISBL.

No. 314,011. Patented Mar. 17, 1885,

NV PETRS. Pholwblhognpher, Wnhngtnn, D. C.

U-Nrrnn STATES y PATENT Ormea.

PHILO L. FOX, OF BRIDGEIORT, CONNECTICUT.

LocK-ivioRTlSiNe CHisEL.

SPECIFICATION forming part of Letters Patent No. 314,011, dated March 17, 1885.

(No model.)

T0 (LZZ whom, t may (2o/warn:

Be it known that I, PHILo L. FOX, a citi- Zen of the United States, residing at Bridgeport, in the county of Fairfield and State of Connecticut, have invented certain new and useful Improvements in Locl-Mortising Chisels; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to that class of woodworking chisels which are adapted for use in making mortises, and are more especially adapted for mortising locks into doors, win dow-sashes, Src., or any uses in which mortises are required to be made in light wood-work, it being desirable in this class ofwork to bore as few holes as possible, to bore them no deeper than is absolutely necessary, to cnt away the surplus wood without prying against the edges of the mortise, and to remove the chips from the bottom of the mortise and render it smooth.

Heretofore, so far as I am aware, straight chisels only have been used, the edges of which have been formed by beveling olf the' metal upon one side, leaving the other side straight. This style of chisel, however, is not well adapted to the making of lock-mortises, for the reason that more holes are required, and they have to be bored deeper, owing to the fact that it is impossible to cut away the wood at the bottom of the mortise with a straight chisel, it being only possible to scrape the bottom by prying against the sides and ends of the mortise, and this can only be done when the wood at the bottom has been splintered by the boring ofnumerous holes. It will be seen, therefore, that when a straight chisel is depended on in this class of work, there is a double waste of time, first, in boring numerous holes and boring them deeper than the mortise; and, second, in attempting to clear away the splinters at the bottom ofthe mortise with a chisel which is not adapted to that especial use. lt is moreover practically iinpossible to avoid mai-ring the edges of the inortises, and in light doors it is not infrequent to split out the sides of the mortises in attempting to clear the bottoms with astraight chisel. In addition to the loss of time, which is a serious loss resulting from the breakage ot' chisels in trying to scrape the bottoms of the mortises by prying against the sides and ends.

The object of my invention is to produce a tool especially adapted to the class of work described above, which shall be no more eX- pensive to make than an ordinary chisel, which cannot be broken in use, and which will cut the ends and smooth the bottoms of mortises without t-he slightest danger of marring the edgesv thereof.

With these ends in view I have devised the novel construction which I will now describe in connection with the accompanying drawings, forming part of this speciiication.

Figure l is a side view, and Fig. 2 an edge view, of my improved chisel.

A is the blade, and B the shank.

The peculiarity of construction is that I forni the outer end ot' the blade in a continuous curve in the same plane as the straight portion and form a cutting-edge by beveling oi1 the inner side, as at C. The strain when in use comes upon the outer side ot the curved portion at about the middle ot' the curve, as indicated 'at D. It will ot' course be understood that the exact curvature to be given to the blade is not a matter ot` vital importance, although I preferably shape the blades about asindicated in Fig. l. I preferably make the whole of the curved portion of the blade of steel, and proportion the blade about as indicated, thus making the breaking of a blade a practical impossibility. I have found in actual practice thatI could putin two locks with this chisel to one with an ordinary straight chisel, and without the slightest danger of breaking out the mortise or breaking the chisel. In using a straight chisel to clear the bottom of an ordinary lock-mortise it is cus tomary to bore tive or six holes, while with -is unavoidable in using` astraight chisel,there I my improved chisel but three holes are neces sary.

Having described my invention, I claimy1. A chisel-blade formed in a continuous curve at its outer end,whereby a bearing-sur- IKO face is formed, as at D, and provided with a l the Curved portion, substantially as and for ro Cutting-edge at its point, substantiall y as dethe purpose set forth. scribed. In testimony whereof I ax my signature in 2. A chisel-blade havingastraight portion, presence of two Witnesses. 5 A, and formed in zt continuous curve at its l Outer end to form a bearing-surface, as at D, PHILO L' FOX the sides ofthe straight and curved portions Witnesses:

being parallei, and a cutting-edge being made A. M. VOOSTER,

at the end by beveling off the inner side of WVM. A. JONES. 

